Refractory



lun. uuwlruallluws, .Examiner coATlNG 0R PLASTIC. Cross Relezem@ 1*'6, 193.7.v *Y* G. LEMMERMAN 2,099,342

BEFRACTORY Filed June 29. 1934 INVENTOR.

815mm 5. Emir/mv Patented Nov. 16, 1937 UNITED STATES ATENT OFFICE nEFaAcToRY Application June 29, 1934, Serial No. 733,087

tended for use in contact with molten iron or steel, for example hot top refractories. The invention also has application however to various molded articles not intended to be subjected to high heat.

One of the objects of the invention is the provision of a refractory employing soluble silicate as a binder, which shall b e moisture-proof to a large degree, that is one which shall be capable of being stored for a long period of time without taking up an appreciable amount of moisture, and consequently one which will retain its original hardness and strength indenitely.

Another object is the production of a refractory of this character which may be subjected to sudden temperature changes over a wide range without cracking or breaking.

A further object is the production of such a refractory principally from raw material, as distinguished from manufactured materials, and hence at low cost.

Other objects and features of novelty will appear as I proceed with the description of the invention.

The single figure of the accompanying drawing is a perspective view of a bottom ring for a hot top, which constitutes an example of a refractory article embodying the invention.

In the drawing I have shown the application of the invention to bottom rings for hot tops employed upon ingot molds, that is to say lining rings for the protection of the lower ends of the hot top casings, and for insulation purposes. These rings are of course subjected to the action of molten steel, and it is important that they should be able to withstand the high heat of the metal Without spalling or breaking, because the dropping of refractory material into the metal might ruin a costly ingot. It is furthermore important that these rings have good heat insulating properties in order that the metal when poured may remain molten in the hot top, and particularly at the lower end of the hot top, for a period long enough to effectively prevent piping in the ingot proper. Good functioning of the hot top in this respect appreciably increases the yield and hence decreases the cost of the steel produced.

The ring herein illustrated constitutes one element of a lining for a hot top casing. 'I'he other elements may or may not be constructed of the same refractory.

Refractory rings for the purpose above mentioned have been constructed heretofore by the methods and of the materials described in Charman and Ward Patents Nos. 1,956,894 and 1,956,895, and in my copending application Serial No. 713,151, led February 27, 1934. In certain cases a manufactured product, that is to say zinc 5 oxide or the like, has been used to render the molded rings moisture-proof. I have now discovered that by substituting a certain natural or raw material for a `portion of the sand used in the rings previously manufactured, I can obtain equally good water-proofing characteristics, while considerably improving the heat insulating qualities and materially reducing the weight of the article, all at a lesser cost.

As in my previous application, I employ a suitable aggregate, preferably silica sand of a rela- 'tively ne grade, washed o remove impurities. Other materials mentioned in the said application may be `substituted for the sand, provided they are chemically inert to the binder. As a binder I prefer to use a soluble silicateI preferably sodium silicate water g ass aving a water content of 60% to 65%.

The sand or other aggregate forms by far the greater proportion of the material used in the previously manufactured rings. In accordance with the present invention I replace a considerable portion of it with a shale which must be free from oil and also m sulphur. For this purpose I prefer to use a certain oil bearing shale which has been burned to remove e o1 s ma ena mgnown o e ra e as aydite. The shale in fact constitutes a part m aggregate, but it is not chemically inert to the water glass. -On the contrary, some of its ingradients combine with the water glass in such manner as to render moisture-proof articles molded from the composition and then dried.

If the shale be an oil bearing shale, as is Haydite, the burning operation is performed, driving off the oil and leaving the particles quite porous. On account of this porosity the volume of the material for a given weight is much greater than that of sand. I crush this material before using it. .4-5

The chemical analysis of Ha dite which is an example of a shale that is we u1 to the purpose, is as follows:

Percent Silica (S102) 65.40 50 Alumina (A1203) 12.30 Iron oxide (Feroz): 13.30 Lime (CaO) 5.20 Magnesia (M60) 2.77 Alkalies (AsNazO) 0.65

A sa

` .L n l "uw I have found that when a shale of this kind in by weight of the sol silicate solution. 'Ihis proper proportions is thoroughly mixed with upon iuse um silisand and made up into molded articles with a cate water glass having a water content of 60% water glass binder, the resulting articles have to 65%. Below such critical point the water- 5 much greater strength than does the shale and proong effect of the sulphate increases as the water glass alone, and that they have much better quantity increases. A material excess of sulheat insulating qualities than does sand and phate above the critical point has a deleterious water glass alone. 'I'he water-proofing qualities eifect upon the binding qualities of the silicate. of the material are apparently due to the pres- 'I'he precise eect of the ferrous sulphate or its ence of the metallic oxides. 'Ihe insulating qualiequivalent in this method is somewhat open to ties are due in part, at least, to the pores left by conjecture. It may be that it unites with the the burning off of the oil. soluble silicate to produce an insoluble silicate,

The relative proportions of shale and sand may or it may be that it acts as a promotor` for other vary considerably, that is to say anywhere from chemical reactions. At any rate, the sulphate l5 5% shale and 95% sand to 80% shale and 20% has an important effect upon the product in that san e stren improves some extent it assists in the water-proong of the product. with an increase in the proportion of sand, and In a 1000 pound batch the weights of the giifgthe insulating qualities improve materially with ent in edient may be said, by way of examp e an increase in the proportion of shale. At the merely, 5e' as follows:

present time I prefer a mix in which shale and Sand or other aggregate Haydite 480 lbs. or 48% 320 lbs. or 32% sand are in the proportion of 400 an sgivesa 'a' rin an one avingms a properties equal to tese of brick It is also glass 177 12%5'1551 highly resistant to moisture and hence remains Ferrous sulphate hard in storage.

When the rings as heretofore constituted are subjected to the heat of molten metal the diy w 3 lbs. or .3%

After dryin silicate binder tends to fuse, with the result that proportions stated will b s bstantially as folthe rings lose most of their strength. In the lows:

rings of the present invention the same tendency Per cent is present, but the heat of the molten metal also Sand or other aggregate 56 tends to soften the shale, and this softened shale Haydite 37 forms a mechanical bond which is highly effective. Dry silicate equivalent 'I When the shale and sand are thoroughly mixed,

water lass in the proportion of 6% to 20% by me entire mass is added, together with Water' and the g res ed until au of the invention fully, but I desire it to be understood that such detailed disclosures are not to be coningredients are intimately commingled. The articles to be manufactured are then molded and strued as amounting to hmitatlons except as they 4o compacted, after which they are dried in an magfnllfsegcfgn claim, oven. 'I'he temperature of the drying oven may vary with the length of time the molded article 1' A molde@ and dxled refractory havnig a remains in the oven It should be high enough water glass binder, said refractory comprising to drive off the moisture but not high enough to shale burned to provide porosity and an aggregate chemically inert to the water glass, said shale 4512711225225; lnslitgl and destroy the bmdmg quali' and aggregate constituting together from 90% Refractories made in accordance with the foreto 99% by welght of the entlre refractory' 2. A molded refractory which comprises the going method are quite water resistant, and may 1 be stored for a reasonable time without absorbfol owing ingredients m the followmg propor tions by weight: silica sand from 11% to 94%, mg an appreciable amount of moisture. However, I prefer to add to the mix a very Smau shale burned to provide porosity from 5% to 80%,

and dry alkali silicate from 1% to 9%. quantity of a soluble sulphate, preferably f rrous ha e other lphas which may be su s 1 3. A refractory comprising the following in ed for the ferrous sulphate are erric sulEhate.i

In the foregoing description I have necessarily gone somewhat into detail in order to explain the gredients in approximately the following proporand sulphates of the following me a s: zinc co tions by weight, aggregate and shale together r e an a inum. The quantity of e sulphate to be used is very 93%, said shale being burned to provide porosity,

small comparatively, and bears a direct relation and dry alkali silicate 7%.

4. A refractory body in molded and dried form comprising sand and the burned porous residue of tonie qilantlty of slhcate. Smce the quantity of an oil-bearing shale which contains a substantial nclat m the T013?? ctllay gibbetwersl proportion of metal oxide, and an added alkali au y arge hun s 1 1s. C o pr e limi silicate binder, said shale residue being capable letlaulanylso imloltantoog'ivg of combining with the silicate when the body is silicate content must notecertain critical dned to form a composlte binder for the sand point, which is in e ne g or o o e or e ROBERT G. LEMMERMAN.

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